How do I model a Mini-Split, Multi-Split or VRF System for Residential Applications?

For mini-split, multi-split and VRF systems the CEC Compliance Manager simulates these internally as a system equivalent to the standard minimum efficiency split system A/C with a fully ducted system in the attic, thus affording no credit towards compliance. When inputting these systems, each Indoor unit should be input at the System level of the Tree as its own System (using the efficiencies from the Outdoor unit), with a corresponding Zone, thus allowing for the necessary rater field verification.  The Outdoor unit should not be input.  At the Central System library, cooling tab, the unit should be identified as Mini-Split, Multi-Split or VRF, to ensure correct reporting.

You have the option to take additional compliance credit for these systems as a VCHP (Variable Capacity Heat Pump) system.  In the case of a VCHP, which requires an indoor unit installed in each habitable room over 150 sqft, we offer the checkbox at the System level of the Building Tree, Residential tab.  Note however that when using this feature, changing the efficiency will not impact the VCHP credit.

You will see the VCHP verification criteria on the CF1R under HERS Feature Summary, and a new section “Variable capacity heat pump compliance option – HERS Verification” on the CF1R, including a comprehensive list of HERS measures for verification.  Our sample file Single Family Mini-split Example  demonstrates this feature.

Appendix B of the VCHP CEC staff report is entitled VCHP Compliance Credit—Eligibility Verification Protocols. This document describes the criteria to be met and is available from the newly established CEC website dedicated to VCHP.

Categories: 4. Single Family Title 24, 5. Multifamily Title 24
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